House dust mite

(Dermatophagoides sp., fam. Pyroglyphidae)


House dust mites are very small creatures, usually less than 0.5 mm long, which have 6 legs as larvae and 8 as adults. They are part of the arachnid class.

House dust mites usually start as eggs, then go on to become larvae before going through various nymph stages and then finally becoming adults. However, special survival forms can also develop, which can withstand unfavourable conditions for a very long time. If the living conditions are ideal, this usually leads to mass reproduction.



House dust mites can be found predominantly in rooms with a high level of humidity. Their scientific genus name “Dermatophagoides” means “skin eater” and indicates their diet. They feed on the flakes of skin which humans shed at a rate of around 0.5 to 1 g per day. The mites cannot digest these directly; they therefore rely on microorganisms to predigest them. The mites therefore always appear together with these microorganisms, e.g. various types of mould.

For sensitive people, they lead to asthma and skin conditions and cause the house dust mite allergy. In this case, the allergens actually come from the mould, which is ingested by the mites and excreted again with the faeces.